Hives are itchy wheals (welts) that erupt on the skin and are usually caused by an allergic reaction.
Hives, also known as urticaria (ur-tuh-KARE-e-uh), develop as a reaction to various stimuli * . Certain foods, food additives or dyes, drugs, alcohol, or viral infections can cause hives in susceptible people. Foods that commonly cause hives include milk, eggs, shellfish, strawberries, other fruits, and nuts.
Penicillin and aspirin cause hives in some people. Some viral infections that are known to cause hives are hepatitis (inflammation of the liver), infectious mononucleosis, and German measles (rubella).
Some people develop hives after vigorous exercise that causes them to sweat. Sometimes the sun or cold air can cause hives to appear on people's skin. In some people, diving into cold water can result in severe hives, a condition known as cold urticaria.
The first symptom of hives is itching, after which the wheals appear. Wheals usually are small, white welts with red, inflamed areas surrounding them; in some cases, however, they can be quite large. They usually erupt on the arms, legs, and trunk. Sometimes they develop into a ring, with the center clearing before the outer ring improves. Hives tend to come and go on different areas of the skin, and individual welts can last several hours.
Most cases of hives clear up by themselves in one to seven days. Some cases respond to medications such as antihistamines * or corticosteroids * . Antihistamines are used to combat the allergic reaction, and corticosteroids are used to fight the inflammation.
The only way to prevent hives is to avoid a known trigger (the substance that sets off the reaction).
See also Allergies • Skin Conditions: Overview
Cerino, Vicky. “UNMC Study: Vitamin D Provides Relief for Those with Chronic Hives.” UNMC Newsroom, February 17, 2014. http://www.unmc.edu/news.cfm?match=12374 (accessed July 17, 2015).
American Academy of Dermatology. “Hives.” AAD.org . https://www.aad.org/public/diseases/itchy-skin/hives (accessed June 11, 2016).
American Academy of Dermatology. PO Box 4014, Schaumburg, IL 60168-4014. Toll-free: 866-503-SKIN. Website: https://www.aad.org (accessed June 11, 2016).
American College of Allergy, Asthma and Immunology. 85 W. Algonquin Rd., Suite 550, Arlington Heights, IL 60005. Telephone: 847-427-1200. Website: http://acaai.org (accessed July 17, 2015).
* stimuli (STIM-yoo-lie) are things in the environment that excite a person to function, become active, or respond. The singular form is stimulus.
* antihistamines (an-tie-HIS-tuhmeens) are drugs used to combat allergic reactions and relieve itching.
* corticosteroids (kor-tih-ko-STAREoyds) are chemical substances made by the adrenal glands that have several functions in the body, including maintaining blood pressure during stress and controlling inflammation. They can also be given to people as medication to treat certain illnesses.